Find the energy spectrum of a particle in the infinite square well, with potential U(x) → ∞ for |x| > L and U(x) = αδ(x) for |x| < L. Demonstrate that in the limit α ≫ hbar^2/mL, the low energy part of the spectrum consists of a set of closely-positioned pairs of energy levels for α > 0. What is the structure of energy spectrum for α < 0?

Answer True or False for each question. For the three questions indicated also provide a full explanation; this is likely to take at least two sentences.

1) Production of particle-antiparticle pairs ended because gamma ray energy decreased as the U expanded.

2) At the beginning, all the energy in the universe was in the form of neutrinos.

3) By t = 15 min, the Universe had cooled enough that nucleosynthesis ended.

4) In the Bottom-up scenario with Cold Dark Matter, small structures like dwarf galaxies form first.

5) It will be possible to measure all properties of a particle with perfect accuracy if our technology increases.

6) By t = 1 sec, the U contained about 25 % He nuclei and the rest H nuclei . Explain.

7) In quantum physics, Heisenberg's uncertainty principle says that matter and antimatter can appear spontaneously in empty space. Explain.

8) Our U contains mass because for every 10⁹ matter particles it created it also created 10⁹+ 1 antimatter particles. Explain.

Explain the process of binning as it relates to use of a CCD detector. What are the possible advantages and disadvantages of using binning? Include a useful diagram.

A 0.870 m long brass pendulum experiences a 21.0°C temperature increase. (a) Calculate the original period (in s). s (b) What is the change (in s) in the period? s (c) Find the ratio (in h) of the change in period to the original period, and calculate how long a clock run by this pendulum would take to fall 1.00 s behind the correc

1) A rock with a mass of 550 g in air is found to have an apparent mass of 327 g when submerged in water.

a) What mass, in grams, of water is displaced?

b) What is the volume, in cubic centimeters, of the rock?

c) What is the average density of the rock, in grams per cubic centimeter?

2) Suppose 1.95 L of gas at 37°C is under 7.37 × 107 Pa of pressure. How many moles of gas are there in the system?

3)Suppose a woman does 350 J of work and 9400 J of heat is transferred from her into the environment in the process.

a) What is the change in her internal energy, in joules, assuming she does not consume any food?

b) What is her percent efficiency?

You are planning to create an ohmic contact for your new semiconductor device. Unfortunately, in your first attempt the contact shows a diode-like current-voltage characteristic, which indicates that the electrons must overcome a barrier.

(a) Show, using the WKB approximation for a parabolic barrier, that at a doping density of ?? = 1 ⋅ 1016cm-3 the tunneling coefficient T is so small that no carriers are crossing the barrier via the tunnel effect.

(b) To what level do you need to raise the doping concentration so that your barrier thickness will be reduced to 3 nm? What is the Tunneling coefficient for this doping concentration? Hint: The material that was used is Silicon4 (Si) with an effective electron transport mass of m* = 0.26 me and a dielectric constant of ε = 12. The barrier height of the contact is given by ΦSB = 0.6 eV. The problem has been simplified as to not use barrier lowering and doping dependence of the Fermi level in the semiconductor.

8 mins persuasive speech on SELF-DRIVING CARS SHOULD BE ILLEGAL!

• Outline

Consider a photon produced in the center of the sun. (A) How long this
Would it take photon to cross the sun and reach the surface if there was no absorption? (B)
Suppose the photon is continually absorbed and reissued so that its path to
surface can be considered as a random walk process. Assuming that reissues
occur instantaneously after each absorption, estimate the time needed for the photon to reach the
surface.

Select simply supported timber beams (S4S) for the following uniformly distributed line loads and spans. deflection is not to exceed span/240. douglas fir, 200 lb/ft., 24ft span.

1) Define the Triboelectric Series and based on your data determine it for the White, Blue and Al charge producers/proof plane.

2) How does this experiment verify Gauss's Law

3) Who is the mathematician that first related conservations laws and symmetry in physics? Write a paragraph on this person using correct citation for references

4) What is the symmetry that is related to charge conservation? use correct citation for references

5) What does the Faraday Ice Pail experiment tell about charge induced on a conducting shell?

6) What does the Faraday Ice Pail experiment tells about the total E field inside a hollow conducting shell if there is charge outside but no charge inside the hollow portion ?

7) How can the answer to question to the previous question be used to create a field free room to house very sensitive electronic measuring equipment?

Explain why the classical theory of light as an electromagnetic wave (or of electrons as particles) is unable to explain the following phenomena whereas quantum mechanics is successful.

1. (1) The turn-on voltage of differently colored LEDs

2. (2) The existence of transparent conductors

3. (3) The decrease in frequency of photons scattered off of atoms

4. (4) The spectrum of blackbody emission

For each, use 2-3 sentences, 1-2 equations, and a diagram to provide an explanation that is concise yet precise.

Your kid brother gets a noise emitting toy for Christmas. This toy emits sound at a constant frequency. He attaches the toy to a rope and starts to swing it back and forth. He is facing you. You, seated on the sofa and very annoyed, measure the frequency of the sound as oscillating between 600.0 Hz and 617.75 Hz. Every 2.00 seconds, you hear the sound at the higher frequency. The speed of sound in air is 343 m/s.

(a) What is the toy’s maximum speed? Where does it have this speed?

(b) What is the length of the rope that the toy is attached to?

(c) What is the maximum height the toy reaches?

(d) Far in the future, a young Martian plays with a similar toy on a terraformed Mars. How many seconds are there between the high frequency sounds?

Show that momentum conservation follows from translational invariance.